Archive for June, 2009

Last week, the Old Calculator Museum received a very special calculator as an addition to the museum’s inventory. The machine received was a 1965-vintage Wanderer Conti printing electronic calculator.

Back in early November of 2008, the museum was contacted by Mr. Hans Boeck, indicating that he was in possession of a Wanderer Conti electronic calculator that was demo machine used by Mr. Boeck when he was involved in sales of electronic calculators in the international market. Mr. Boeck had indicated that he would be interested in donating this machine to the Old Calculator Museum. Due to a number of complications, it took quite some time for the machine to finally make its way to the museum. It arrived completely intact, a testimony to the incredible packing job done by Mr. Boeck. The Old Calculator Museum owes a supreme debt of gratitude to Mr. Boeck for making this wonderful artifact available to the museum. The Conti is a rather rare machine, and while it was sold in the US by Victor Comptometer (under OEM agreement with Wanderer-Werke) as the Victor 1500-Series, there just are not very many of these machines left around today. The museum has been looking for an example of a Conti (or the Victor or Sumlock Comptometer-badged versions of the machine) for many years. Had it not been for Mr. Boeck’s kindness and generosity, the search may have gone on for a very long time.

The Wanderer Conti was the first electronic printing calculator to print on “adding machine-style” paper tape. The Mathatronics Mathatron is historically recognized as the first printing electronic calculator, but it printed on a special 5/8ths-inch wide “ticker-tape” style paper tape. While the Mathatron had the distinction of being the first marketed printing electronic calculator, the ticker-tape style printout was somewhat unwieldy for storage and reading, while the adding machine tape printout of the Conti was something that was much more familiar to accountants and bookkeepers. The Mathatron was more targeted at scientific and engineering calculations, while the Conti was more targeted toward business use.

Wanderer-Werke AG, a company founded in 1885 in Koln, Germany, started out manufacturing bicycles. The business thrived, and into the early 1900’s, the company had expanded into making typewriters, milling machines, and by 1910, had started making automobiles and motorcycles. The company became known in Europe as a premier manufacturer of mechanical products of superb engineering. In 1927, the company began manufacturing adding machines, further expanding their business base, and making a name for itself in the European business machine marketplace. During World War II, Wanderer-Werke was a principal manufacturer involved in the German war effort. After the war ended, the company went back to its core businesses. Wanderer-Werke AG still exists to this day, serving primarily as a financial holding company for a number of businesses, as well as licensing the Wanderer brand name for use by outside companies.

With the advent of the first marketed desktop electronic calculator, the Sumlock Comptometer/Bell Punch ANITA in late 1961, many makers of mechanical adding machines and calculators began to realize that their future in the business machine marketplace may be radically affected by the advent of electronic means of calculation. It so happened that one of Wanderer-Werke’s major customers was another German company, Labor Für Impulsetechnik, also known as LFI. Founded in 1952 by Heinz Nixdorf, a brilliant electrical engineer and businessman, LFI developed complex electrical and electronic control systems for industry. Mr. Nixdorf had a keen interest in computers, and moved his business into developing electronic computing devices, developing early business-oriented small computers and accounting machines. Sometime in 1962, and arrangement was made for LFI to design the electronics for Wanderer-Werke to use in making their own electronic calculator.

LFI had a world-class electronics design operation, and had become masters in the art of designing logic circuitry based on transistors. Up until 1958, Mr. Nixdorf was the chief electronics engineer for the company, but after that, he had to start hiring engineers to help with the design process, as there was simply more work than he could handle by himself. LFI designed all of the transistorized electronics for the machine to specifications jointly developed by Wanderer-Werke and LFI. In late 1964, the first Conti (which derived its name from Wanderer’s line of “Continental” typewriters), was introduced in Europe, and was quite successful due to its convenient printing operation, high speed, and memory capability. In 1965, Victor Comptometer signed up as an OEM distributor of the machines in the US (marketing the machines as the Victor 1500-series calculators), and later (1967) Sumlock Comptometer in the UK also distributed the machines to provide a printing calculator to their existing line of Nixie-tube display calculators.

The design that was developed was truly a work of digital design art for the time. The calculator’s architecture was a bleeding-edge example of computing machine design, using a microcoded architecture centered around a wire-rope ferrite core ROM for controlling the operation of the machine (14x16x80, for a total of 17920 bits of ROM), magnetic core memory (16x14x4, totaling 896 bits), and completely transistorized control logic and arithmetic unit. At the time of its introduction, there was no other machine on the market that could match the Conti as far as the advanced computer-like architecture used in its design.

The resulting machine was built to the extremely high standards of German manufacturing processes. The design is very modular, with the electro-mechanical keyboard and printer assemblies, and power supply module stacked neatly atop the electronics. The electronics are in the form of three large circuit boards, arranged in plastic frames and “bound” at the long edge such that the boards form a “book”. The boards are interconnected by hand-wired connections along the spine of the book, along with four very high quality edge connector sockets that make up the backplane connections as well as the connections between the keyboard/printer, power supply, and electronics. The power supply takes up the right-hand side of the chassis, the printer situated in the center, and the keyboard mechanism at the front of the machine. The electronic design is based on Silicon transistors, making the Conti the earliest electronic calculator based on this transistor technology. Other electronic calculators of the time were based on earlier Germanium-based transistor technology, that used more power, operated at slower speed, and tended to be less-reliable than Silicon-based transistors. The speed of the Silicon transistors, combined with the efficient microcoded architecture of the machine made the Conti a very fast calculator. Additions and subtraction took just over 1 millisecond (1/1000th of a second), and multiplication and division took between 60 and 70 milliseconds. By comparison, the Friden 130 was roughly 20 times slower on average. Of course, the Friden machine displayed its answers on a CRT display, giving virtually instantaneous results once the calculation was completed, while the Conti had to take the time (roughly 300 milliseconds) to print its results, but for the extra time spent, the Conti gave a permanent record of its calculations, something the Friden and most all other calculators on the market at the time could not boast.

The mechanicals of the Conti live up to Wanderer-Werke’s mechanical engineering excellence. The design of the printing mechanism is relatively compact and quite straightforward, using individual print wheels for each column. The print wheels turn to match up with corresponding digit or character needed at that each position, at which time a small solenoid is fired by the electronics to lock each wheel in place. Once all print wheels are in the correct position, the mechanism drives the print wheels up against the ribbon to transfer the line of print to the paper in one shot.

The keyboard assembly is a very complex mechanical assortment of code bars that serve to encode the keys, switch contacts to turn the mechanical code into electrical impulses, and interlocks to prevent multiple keys from being depressed at once.

While there are different versions of the Conti, they all share some common features. The machines have a capacity of 14 digits. Internally, 16 digits are used (the machine uses a 4-bit “word” to encode each digit), with one digit representing the sign of the number, fourteen digits making the number, and a final digit used as a “check” digit by the electronics as an error-detecting means. All of the machines have at least three memory registers, with some models gaining an additional seven memory registers for a total of ten memories. All of the models provide the four standard math functions, with some models able to calculate square roots with one-touch ease. Fixed decimal point location is set by a thumbwheel switch. On some models, two thumbwheel switches allow setting of the decimal point location and the digit at which round-off/truncation should occur. The keyboard provides a key for forcing the current number to be rounded off or truncated based on the setting of the round-off switch. Negative numbers are printed in red, using a two color ribbon. The printer has 21 columns, and can print around 3 lines per second. Later models in the Conti line, based on the same basic design, allowed the connection of external peripheral devices such as a paper tape readers (for automatic input), paper tape punches (for recording output of the calculator), other forms of hard copy (slave printers and typewriters), and even magnetic tape drives that would record the calculator’s output to allow it to be fed to computers.

The machine received by the museum has three memory registers, one-key square root, and provides separate thumbwheel controls for selecting the decimal point position and the round-off digit position. It does not have provisions for connection of peripheral devices.

In a competitive analysis document published by Friden Calculating Machine Co. in 1965, Friden commented that there was a lack of information about the machine that kept them from performing a detailed analysis. To this day, this statement is still true, there is very little information out there about these fantastic machines. The authors of the Friden document did comment that in the demo that they saw, the keyboard seemed to be a weak point for the machine, with the comment made that operation of the keyboard seemed less than satisfactory. They also commented that the machine seemed complicated to use, with a large number of control keys.

While the Conti was not a programmable machine, the fact that it was controlled by a microcoded calculating engine meant that it was possible for custom operating firmware to be created for the machine. While not substantiated as ever having been done, the Friden document noted above does mention that customization of the machine can be done, but not by the user. Such customization would likely be done by modifying the content of the microcode ROM to implement customized functions for particular applications.

The machine does have a few minor issues known at this time that need to be worked on. First, there is a cogged belt that connects the main drive motor to the printing assembly. Somewhere along the line, this belt deteriorated, as is common with many rubber-based materials that are exposed to many years of atmospheric contaminants. Unfortunately, this belt is of a size and cog pitch that does not seem to be made anymore, so some effort and expense will have to be expended to have a custom-manufactured replacement made. Also, the main clutch that actuates the printing mechanism doesn’t completely release at the end of a print cycle (as found by manually cycling the machine through a print cycle), meaning that some adjustment of the mechanism is required. Also, the memory register selection keys (three of them) are all locked in the pressed position, which will likely require some mechanical adjustment to remedy. Along with these mechanically-related issues, the machine will need a thorough electronic checkout to assure that all is well with the power supply before even thinking about powering the machine up.

I have written to the Curator of Business Machines at the Heinz Nixdorf Museum in Paderborn, Germany, in hopes that they may have information about the Wanderer Conti calculators. Hopefully this query will result in some materials which can be used to help better document this machine in an upcoming exhibit on the Old Calculator Museum’s website.